"I'm not sure where the snafu happened," says Mendenhall, who's organizing the event.

For decades, the Prayer Breakfast, which operates independently from the governor's office, has drawn lawmakers, ministers and the state's top officials together in what Mendenhall calls a "show of unity" and an opportunity to "reach out to God and ask him to bless our state."

Mendenhall says he was under the impression Bullock would speak at the March 2 event at Carroll College. Programs for the breakfast already listed him as attending. But one day after social media boards and some inside the Capitol questioned Bullock's apparent involvement, Mendenhall says he was notified by the governor's office that Bullock would not be there.

At issue is the breakfast's keynote speaker, David Barton. Barton has garnered national headlines for his revisionist teachings, pro-life advocacy and calls to criminalize homosexuality, all of which would seem to run contrary to Bullock's politics. According to the Southern Poverty Law Center, "The scary thing about David Barton is that he has the ear of so many."

Barton's Texas-based advocacy group, WallBuilders, supports "the Godly foundation of our country" and provides "information to federal, state, and local officials as they develop public policies which reflect Biblical values," according to its website.

Montana LGBT rights activists expressed outrage once word got out that Barton was scheduled to speak at the breakfast. "It's unfortunate that the organizers of the Governor's Prayer Breakfast would choose a man like David Barton to speak about anything," says Jamee Greer of the Montana Human Rights Network.

Mendenhall says he was unaware of any controversy associated with Barton.

Meanwhile, the governor's office maintains it was unaware of Bullock's expected attendance. Deputy Chief of Staff Kevin O'Brien says when breakfast organizers contacted the office last week, "It was the first I had heard of it. And the governor had never heard of it."